This invention relates to packing elements use in mass transfer and direct heat transfer applications and specifically to packing elements of a generally cylindrical shape, such as for example Pall rings.
Such elements are used in reactors where liquids and gases are contacted so as to bring about a reaction, heat transfer, solution or dissolution operations by intimately contacting two flowing fluids. As a consequence they have shapes designed to maximize surface area while retaining dimensional stability such they they do not collapse or become crushed during use. One means of achieving this end is to form the rings from cylindrical metal blanks, and providing internal structure by a variety of suitable techniques.
It is however desirable to have a structure that is easily produced to a standard design in large volumes. To satisfy these requirements the elements are often stamped out of a flat metal plate intended to be bent into a cylindrical shape with a plurality of flaps cut from the plate and bent inwards towards the axis of the cylinder. This is the shape of the typical Pall ring and is described for example in Reissue U.S. Pat. No. 27,217.
In order to retain the rigidity of such a ring it needs to be shaped from a relatively thick metal plate that will have be able to withstand the compressive forces encountered in use. Lacking such rigidity the rings will become compressed under the loading in the tower and more rings will be needed to fill the tower. In addition compressed rings do not have the same performance characteristics such that some predictability in operation is lost.
On the other hand it is desirable to reduce the thickness of this metal plate to save weight and to make the rings less expensive.
One solution has been to use a pair of bridging members to hold two cooperating semicylindrical pieces together as is described in U.S. Pat. No. 4,197,264. This has a significant disadvantage in that the production process requires the combination of four separate components to make the final product.
The present invention provides a relatively rigid packing of the Pall ring type while allowing the use of thinner gauge metal. The ring structure is so designed that it can be made from a single strip of metal in a simple cutting and bending operation readily adapted to the use of mass production techniques.